The invention relates to a swirl element for an inlet valve of a brewing vessel for introducing a liquid into the brewing vessel, and more specifically to a swirl element, inlet valve, device and method for evaporating or driving out highly volatile substances or gases from liquids, and the use of the same in brewing processes.
Degassing of liquids such as, e.g., liquid foods, in particular beverages, traditionally takes place inside a degassing device. Here the liquid is subjected to a reduced absolute pressure, often in combination with a temperature raised above room temperature. In order to achieve degassing of the liquid that is as complete as possible, it is necessary to expose all the volume elements of the liquid to the conditions named in the foregoing. To this end, the liquid is introduced into the degassing device either by spraying or in the form of a thin film.
In document JP 2003-164706 a degassing device is proposed wherein the liquid to be degassed is introduced into a tank-type degassing vessel vertically from above and coaxially with the center axis. A reduced absolute pressure is present inside the degassing vessel. In detail, feeding takes place through an inlet valve arranged in the upper area of the degassing vessel. The liquid enters from the inlet valve into the degassing vessel through a fixedly pre-set annular gap. In the opened condition of the inlet valve, the annular gap is delimited by a valve seat and a valve cone. The valve seat is the lower end portion of the inlet valve housing. The valve cone is adapted to be driven by a control means so as to allow the realization of two valve conditions, namely, a fully opened valve condition and a fully closed valve condition.
When the liquid passes through the annular gap in the opened condition of the inlet valve, the liquid flows across the valve cone into the degassing vessel. The valve cone is configured in the shape of an umbrella having an enlarged diameter in comparison with the inlet valve and sloping down outwardly in a radial direction from the center axis of the inlet valve which is arranged to be coaxial with the center axis of the degassing vessel. The liquid flowing out ideally forms a thin film on the valve cone, with the film detaching at the edge terminating the cone. The freely dropping liquid film then impinges on the inner wall of the degassing vessel and runs off vertically in a downward direction.
From document DE 297 22 673 U1 a device for degassing sensitive foods having a viscous consistency is known, wherein a rotating, cone-shaped disk for creating a thin liquid film is proposed. The diameter of the rotating disk approximately corresponds to the internal diameter of the degassing vessel, with a narrow, annular gap being formed between disk rim and container wall. During the degassing process, the viscous liquid exits through the annular gap and is then distributed on the disk owing to the shear forces acting as a result of the rotating movement. The centrifuging effect of the rotating cone disk brought about by the shear forces thins the liquid layer while forming a flowing film. Across the entire distance from the inlet valve to the disk rim near the container wall, the liquid film is in surface contact on the upper peripheral surface of the disk.
The use of a conventional inlet valve with formation of a liquid film through radial deflection of the flow of liquid on a valve cone is a drawback inasmuch as a film or umbrella-shape formation that is sub-optimal with regard to the removal of gases from the liquid may come about when degassing different liquids and/or under variable marginal physical conditions. When different liquids or liquids of variable composition are introduced into the degassing device with a same inlet device, the different rheological or flow characteristics of the liquids may result in the formation of variously shaped liquid films that will ultimately differ from the film shape that is optimum for degassing. Aside from the physical marginal conditions, the rheological properties and the flow characteristics of a liquid are essentially determined by its composition. The composition is in turn determined by the solvent, in the practical case particularly water or oil, and by the quantity and kind of the dissolved ingredients. In the case of suspensions, the solids content moreover has an influence on the flow properties.
Another drawback of a conventional inlet valve is that a constant volumetric flow rate of the liquid flowing into the degassing device is a precondition for the formation of a liquid film having an optimum thickness. Due to external influences, in particular influences of units arranged upstream or downstream in a continuous production or processing process, however, fluctuations may occur in the volumetric flow rate of the liquid during degassing. A volumetric flow rate differing from the originally projected target value does, however, result in the formation of a liquid film that is not optimum with a view to degassing, and thus in a deficient degassing result.
Besides the deficient degassing results, deviations from the optimum liquid film during the degassing process may also result in increased frothing of the liquid. This may occur in particular if the liquid film impinges on the inner wall of the degassing vessel at an unfavorable, sufficiently steep angle. If frothing inside the degassing vessel attains an intensity where the froth rises to the evacuation mechanism—which is frequently integrated coaxially in the inlet valve—an irregularity of the degassing process and in a given case of the entire production process may occur.
Utilization of a cone disk with a liquid film in surface contact thereon additionally involves complex mounting of an additional component occupying a large space. Furthermore the proposed cone disk requires a complex mount and a mechanically complicated drive mechanism for the rotation of the cone disk. Furthermore, a degassing device having such installations is difficult to clean, which is a drawback particularly in the degassing of liquid foods.
Furthermore it was hitherto not possible to utilize the part of an inner surface in the upper part of the degassing vessel, which was situated above the impact surface of the liquid film, as a degassing surface. This was a limitation to the usable degassing surface, which resulted in an insufficient removal of gas and in larger-sized containers.
Furthermore, in the conventional brewing process liquids such as mash or wort were introduced into a brewing vessel in the form of a pipe flow having a smallest possible surface-to-volume ratio in order to avoid oxygen adsorption. In order to further reduce the introduction of oxygen, the liquid was moreover introduced into the brewing vessel from the vessel's bottom in a direction opposite to gravity. This did, however, only result in a poor effect of evaporating undesirable, highly volatile substances such as certain flavor substances.